U.S. patent application number 13/897154 was filed with the patent office on 2014-11-20 for bend protector for a pipeline bend.
The applicant listed for this patent is Benton Frederick Baugh. Invention is credited to Benton Frederick Baugh.
Application Number | 20140338775 13/897154 |
Document ID | / |
Family ID | 51894812 |
Filed Date | 2014-11-20 |
United States Patent
Application |
20140338775 |
Kind Code |
A1 |
Baugh; Benton Frederick |
November 20, 2014 |
Bend Protector for a Pipeline Bend
Abstract
A protector for protecting the internal bore of a pipeline bend
from a line being pulled through the pipeline bend during servicing
operations including a first liner section which will travel along
the pipeline to the pipeline bend bend but which will not pass
through the pipeline bend, a one or more of second liner sections
which will pass through the bend but are connected to the first
liner section, releaseably connecting the liner sections to a
service pig, pulling the liner sections into the pipeline with the
service pig until the first liner section encounters the bend and
stops, continuing travel with the service pig and releasing the
service pig from the liner sections, and constraining a line
connected to the service pig to be positioned within the liner
sections rather than contacting the pipeline bend.
Inventors: |
Baugh; Benton Frederick;
(Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Baugh; Benton Frederick |
Houston |
TX |
US |
|
|
Family ID: |
51894812 |
Appl. No.: |
13/897154 |
Filed: |
May 17, 2013 |
Current U.S.
Class: |
138/110 |
Current CPC
Class: |
B08B 9/04 20130101; B08B
9/027 20130101; F16L 57/06 20130101; E21B 23/14 20130101; F16L
2101/50 20130101; F16L 57/02 20130101 |
Class at
Publication: |
138/110 |
International
Class: |
F16L 57/02 20060101
F16L057/02; B08B 9/04 20060101 B08B009/04; F16L 57/06 20060101
F16L057/06 |
Claims
1. A protector for protecting the internal bore of a pipeline bend
comprising: a first liner section which will travel along said
pipeline to said pipeline bend but which will not pass through said
pipeline bend and a one or more of second liner sections which will
pass through the bend but are connected to said first liner
section.
2. The protector of claim 1 further comprising releaseably
connecting said liner sections to a service pig, pulling said liner
sections into said pipeline with said service pig until said first
liner section encounters said bend and stops, and continuing travel
with said service pig and releasing said service pig from said
liner sections.
3. The protector of claim 2 further comprising constraining a line
connected to said service pig to be positioned within said liner
sections rather than contacting said pipeline bend.
4. The protector of claim 3 further comprising said line is a
coiled tubing string.
5. The protector of claim 4 further comprising one or more of said
liner sections has a low friction material to engage said coiled
tubing string.
6. The protector of claim 3 further comprising said line is a
wire.
7. The protector of claim 6 further comprising one or more of said
liner sections have one or more rollers to engage said wire.
6. The protector of claim 1, further comprising said pipeline bend
having a center plane defined by the center of said pipeline along
said bend and said one or more of said second sections are profiled
such that said one or more second sections contact said pipeline
bend along two spaced apart locations on each said of said center
plane such that the angle of contact relative to said center plane
causes the normal loading of said contact to be increased and
therefore for the frictional force holding said protector in said
pipeline bend to be increased.
7. The protector of claim 2 further comprising that when said
service pig returns to said pipeline bend, said service pig:
engages said liner sections, and moves said liner sections along
said pipeline.
8. The protector of claim 1 further comprising said liner sections
are installed into said pipeline through a work window.
9. The protector of claim 2 further comprising said service pig is
suited for removing blockages from said pipeline.
10. A protector for protecting the internal bore of a pipeline bend
from a line being pulled through said pipeline bend during
servicing operations comprising: a first liner section which will
travel along said pipeline to said pipeline bend bend but which
will not pass through said pipeline bend, a one or more of second
liner sections which will pass through the bend but are connected
to said first liner section, releaseably connecting said liner
sections to a service pig, (or not) pulling said liner sections
into said pipeline with said service pig until said first liner
section encounters said bend and stops, continuing travel with said
service pig and releasing said service pig from said liner
sections, and constraining a line connected to said service pig to
be positioned within said liner sections rather than contacting
said pipeline bend.
11. The protector of claim 10 further comprising said line is a
coiled tubing string.
12. The protector of claim 11 further comprising one or more of
said liner sections has a low friction material to engage said
coiled tubing string.
13. The protector of claim 10 further comprising said line is a
wire.
14. The protector of claim 13 further comprising one or more of
said liner sections have one or more rollers to engage said
wire.
15. The protector of claim 10, further comprising said pipeline
bend having a center plane defined by the center of said pipeline
along said bend and said one or more of said second sections are
profiled such that said one or more second sections contact said
pipeline bend along two spaced apart locations on each said of said
center plane such that the angle of contact relative to said center
plane causes the normal loading of said contact to be increased and
therefore for the frictional force holding said protector in said
pipeline bend to be increased.
16. The protector of claim 10 further comprising that when said
service pig returns to said pipeline bend, said service pig:
engages said liner sections, and moves said liner sections along
said pipeline.
17. The protector of claim 10 further comprising said liner
sections are installed into said pipeline through a work
window.
18. The protector of claim 10 further comprising said service pig
is suited for removing blockages from said pipeline.
Description
TECHNICAL FIELD
[0001] This invention relates to the method of protecting a bend in
a pipeline from abrasion and galling due to the drag friction of a
tubing string or wireline which is pulled through the pipeline
bend.
BACKGROUND OF THE INVENTION
[0002] A majority of offshore oil and gas is produced form
platforms which are erected on the seafloor and extend to above the
water surface. Oil and gas is typically transported to and from
these offshore platforms along pipelines laid on the seafloor. When
these pipelines arrive to or depart from one of these platforms, a
bend is used at the intersection of the seafloor and the platform
and a vertical section of pipe or riser extends up to the platform
deck. At the platform deck will be valves and piping to communicate
the pipeline with equipment and/or wells on the deck of the
platform.
[0003] Subsea pipelines which transport oil tend to have the waxy
components of the oil come out of solution and bond to the wall of
the pipeline, up to in some cases completely blocking the
pipelines. In consistence, the waxy blockage appears to be exactly
like black shoe polish. In most cases, a layering on the walls of
the pipeline is seen and a cleaning pig passes through the pipeline
to remove the waxy layering. In some cases instead of simply
cleaning the layer of wax off the pipeline wall, it chips it off
until it accumulates into a blockage.
[0004] When subsea pipelines which transport gas encounter the
proper pressure/temperature combination and there is some water in
the pipeline, a hydrate is formed. The hydrate looks a lot like
crushed ice and will form quickly to create a blockage to stop the
flow in the pipeline.
[0005] In either of these cases the flow of production is stopped
and causes an expensive loss of production. In the case of a
hydrate blockage, the operator can simply wait a few days, weeks,
or months and the hydrate will melt naturally if pressure is bled
off from one end or the other of the pipeline. In the case of the
waxy or paraffin blockage, it is permanent until fixed.
[0006] As "fixing" these problems typically required mechanical
drilling of the blockage, hot oil injection, or chemical dissolving
of the blockage, communication to the blockage in the pipeline must
be established. The characteristic way to establish this
communication is by inserting a string of coiled tubing. A hose
would work as well, but the strings of coiled tubing for up to 5
miles in length exist in the market. The hoses do not exist in the
market at this length, and would be very expensive in comparison if
they did.
[0007] Crawford U.S. Pat. No. 6,651,744 shows a coiled tubing
string with a thruster pig (10) attached to the end for this
purpose and illustrates in FIG. 12 the coiled tubing reel (150),
and various other pieces of required equipment. Of note is a 5D
bend section (15) which is at the intersection of the seafloor
pipeline and the vertical riser. "5D" means that the bend radius of
the centerline of that pipe section is 5 times the outer diameter
of the pipeline. Sending equipment down the vertical pipe section
around the 5D bend and then going out up to 5 miles is a very
difficult goal to achieve, and is a common requirement of many
offshore pipelines. If you imagine that in a 4.5 inch outer
diameter pipeline this bend radius is 22.5 inches, then the steel
coiled tubing must negotiate this bend.
[0008] The first problem in navigating this bend is that bending 1
to 13/4 inch outside diameter coiled tubing to a radius of 22.5
inches substantially bends and unbends the coiled tubing as it
passes, both going and coming back which has a deteriorating effect
on the coiled tubing. Secondly, the high loading on the inside of
the pipeline bend and the outside diameter of the coiled tubing
when it is being plastically bent tends to cause galling on both
pipes, which destroys the integrity of whichever one(s) is galled.
Thirdly, the force of pulling the coiled tubing back through the
bend from its extended travel position is added to the force of
pulling the coiled tubing back, pulling the pig back, and swabbing
the fluid behind the coiled tubing back. At some point, you simply
cannot pull the coiled tubing back and have caused a worse problem
than the blockage itself.
[0009] When any or all of these factors is a concern, the only
solution is to pick the pipeline up off the seafloor, saw it in
half, and attach expensive connectors to the pipeline. This allows
the operator to go directly into the end of the pipeline without
having to pass a difficult bend. A complication to this is that
before the operator can saw the pipeline in half, the pressure must
be completely removed from the pipeline. Additionally, as you are
sawing into a pipeline with at the least gas fumes in it, you may
cause a spark.
[0010] An additional problems when going around the pipeline bends
is that any equipment to pass the bend must be by definition very
short or it simply will not pass and the bending of the coiled
tubing tends to import moment loading on the equipment, such as the
thruster pig at the end of the coiled tubing.
[0011] Offshore platforms with vertical riser pipes have been
utilized in the offshore industry as long as it has existed, since
the mid 1950's. Coiled tubing became available as an oilfield
service tool in the mid 1960's and the marriage of these two
systems happened shortly thereafter. The industry is still dealing
with the problem of how to reasonably get the coiled tubing around
the bends, and the most common answer today is to expensively pick
the pipeline up and avoid the problem.
BRIEF SUMMARY OF THE INVENTION
[0012] The object of this invention is to provide a method of
installing a protective liner in the bend between a subsea pipeline
and a vertical pipe riser at a platform.
[0013] A second object of this invention is to provide a method of
protecting a thruster pig from the side forces resulting from the
bend in the coiled tubing after going through the bend between a
subsea pipeline and a vertical pipe riser at a platform.
[0014] A third objective of this invention is protect the sealing
cup of a thruster pig from being heavily worn on one side due to
the weight of the thruster pig.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a partial half section of a subsea pipeline and
the vertical riser which would be near an offshore platform, with
service equipment to facilitate this method landed on the top of
the vertical riser.
[0016] FIG. 2 is the partial half section of FIG. 1 with the work
window opened and a thruster pig assembly being inserted into the
bore.
[0017] FIG. 3 is the partial half section of FIG. 2 with the
thruster pig assembly fully inserted into the bore.
[0018] FIG. 4 is the partial half section of FIG. 3 with the end of
the coiled tubing string engaging the thruster pig assembly and a
bend liner being connected to the thruster pig assembly.
[0019] FIG. 5 is the partial half section of FIG. 4 having the
thruster pig assembly run down into the bend at the base of the
vertical riser.
[0020] FIG. 6 is the partial half section of FIG. 5 with the
thruster pig assembly out of the bend and into the pipeline, and
the bend liner in the bend.
[0021] FIG. 7 is the partial half section of FIG. 6 with the
thruster pig assembly released from the bend liner and running out
into the pipeline. The bend liner is protecting the bend from
damage by the coiled tubing passing through.
[0022] FIG. 8 is a half section of a bend liner in the curved shape
which it would have when it is in the bend.
[0023] FIG. 9 is a section of the bend liner of FIG. 8 taken along
lines "9-9".
[0024] FIG. 10 is a section of the bend liner of FIG. 8 taken along
lines "10-10".
[0025] FIG. 11 is a half section of one of the sections of the bend
liner with rollers substituted for the low friction material to
make it better suited to accommodate a wire rope.
[0026] FIG. 12 is half section of a thruster pig assembly which is
similar to the thruster pig assembly first shown in FIG. 2, but is
adapted to be in the central portion of the coiled tubing string
rather than at the end and is adapted to assist in pulling the
coiled tubing back rather than pulling it out to the blockage
site.
[0027] FIG. 13 is an enlargement of the central portion of FIG.
12.
[0028] FIG. 14 is the thruster pig assembly of FIG. 12, but being
shown passing through a pipeline bend.
[0029] FIG. 15 is an enlargement of the central portion of FIG.
14.
DETAILED DESCRIPTION OF THE INVENTION
[0030] Referring now to FIG. 1, a half section view of a complete
system 10 on the side of an offshore platform (not shown) which is
prepared for the method of this invention. Seafloor pipeline 12 has
a blockage 14 at some distance from the bend 16 at the base of a
vertical riser 18. Vertical riser 18 has a top flange 20 with
pressure control equipment 22 landed on top of it. Pressure control
equipment 22 represents valves during regular production and
blowout prevention equipment during service operations. Above
pressure control equipment 22 is a working window 24 and service
equipment 26 above that. Working window 24 is a pressure vessel
with side openings to allow the insertion of tools into the well
bore. Service equipment 26 comprises a variety of items which will
change from location to location. These items might include a
stripper for sealingly engaging the coiled tubing, slips to
temporarily support the coiled tubing or to stop the coiled tubing
in an emergency, a coiled tubing injector head to push or pull the
coiled tubing into our out of the pipeline, etc. Coiled tubing 28
is shown entering the top if the injector head, but is not shown
having gone in far enough to be seen in the control equipment
20.
[0031] Referring now to FIG. 2, doors 40 and 42 have been opened by
releasing bolt 46 and thruster pig assembly 48 has been started to
be placed into the bore 50. Thruster pig assembly 48 comprises
thruster pig 52, ball joint 54, and coiled tubing connector 56. It
should be noted that both thruster pig 52 and coiled tubing
connector 56 include a ball joint mechanism to allow the
flexibility to allow this operation thru the work window 24.
[0032] Referring now to FIG. 3, thruster pig assembly 48 is fully
in bore 50 and is temporarily supported on bars 60. The lower end
62 of coiled tubing 28 is being lowered to engage the coiled tubing
connector 56.
[0033] Referring now to FIG. 4, the lower end 62 of coiled tubing
28 is engaged with coiled tubing connector 56 and the end 70 of
bend protector 72 is attached to the coiled tubing connector 56.
The likely method of connection will be with a shear pin which will
be discussed later.
[0034] Referring now to FIG. 5, coiled tubing 28 is lowered until
the bend protector 72 is fully within bore 50, doors 40 and 42 are
closed, bolts 46 are engaged and tightened, thruster pig assembly
48 is in the bend 16, and the bend liner is following.
[0035] Referring now to FIG. 6, thruster pig assembly 48 is not
fully in the pipeline 12 and bend protector 72 is in the bend 16.
Sections 74 of bend protector 72 are short enough and flexible
enough to pass through the bend 16. Section 76 of bend protector 72
is long enough and is of a shape such that it will not navigate the
curve of bend 16 and therefore acts as a position stop to cause the
bend protector 72 to remain in bend 16 as thruster pig assembly 48
travels out into the pipeline. When thruster pig assembly 48
returns to the bend 16 it will engage the bend protector 72 and
push it back up the vertical riser 18.
[0036] Referring now to FIG. 7, additional pressure for force
applied to thruster pig assembly 48 causes it to release from the
bend protector and travel further into the pipeline. As the
thruster pig assembly 48 travels into the pipeline and pulls the
coiled tubing behind it, the bend liner 72 protects the bend of the
pipeline from wear and galling by the coiled tubing.
[0037] Referring now to FIG. 8, a half section of the bend
protector 72 as was shown in FIG. 7 is shown in greater detail.
Section 74 is shown as individual sections 74A-74F. Each of these
individual sections has an insert 80 of low friction material such
as Teflon provided in a curve generally matching the curve of the
bend 16 to slide the coiled tubing against. The coiled tubing will
be engaging a surface 82 of a low friction material and the
individual sections 74A-74F will be engaging the bend 16 with a
steel on steel contact to insure that the bend liner 72 will remain
in place when the coiled tubing is travelling out, or is coming
back. Similarly, section 76 is outfitted with a low friction insert
84 with surface 86 for engaging the coiled tubing. End 70 of bend
protector 72 has a shear pin 88 for attaching to coiled tubing
connector 56 on the end of the thruster pig assembly 48 as seen in
FIG. 4. The shear pin 88 is conveniently in this case a hollow pin
which threads into both pieces so that no loose pieces will be left
in the pipeline.
[0038] Referring now to FIG. 9 which is taken from section "9-9" of
FIG. 8, coiled tubing 90 is shown bent around and engaging surface
82. Pin portions 92 and 94 act as connections and pivots between
individual sections 74C and 74D and can be round pins welded into
holes on individual section 74C. Spring pin 96 would be inserted at
each end of insert 80 to retain it in position. It can be noted
that individual sections 74C and 74D do not contact the pipe bend
16 at the center position 98, but rather clearance 100 allows it to
contact at 102 and 104. This angular contact amplifies the force of
contact to give an ever greater difference in the forces as was
discussed with respect to FIG. 8. The force 106A of coiled tubing
28 around the bend of pipe happens in the plane 106B as indicated
by section line "8-8" passes through the centerline 106C of
pipeline bend 16, however it is supported at contacts 102 and 104
as forces 106D and 106E which are each shown graphically as 1/2 of
the force 106A. Forces 106F and 106G are the normal to the surface
forces associated with forces 106D and 106E respectively, and they
are larger by the inverse of the cosine of the angle 106H, meaning
that the friction force causing normal contact force has increased
assisting the bend protector in remaining in position as the coiled
tubing is pulled back through the pipeline bend 16. This angular
contact can be pushed to about 45 degrees to each side which would
amply the force about 41% over plain steel on steel contact.
[0039] Referring now to FIG. 10, shear pin 88 is illustrated as an
all thread brass piece with a hex 108 broached all the way through
to make it easy to install, remove and to shear. This style
construction means that both ends of the shear pin will be
positively restrained rather than being lost in the pipeline to
cause other problems.
[0040] Referring now to FIG. 11, individual section 110 is shown
with rollers 112 A-D being mounted on axles 114 A-D rather than
having an insert 80 of low friction material such as Teflon. A wire
rope 116 is shown being guided in the rollers 112 A-D. As a wire
rope such as 116 is often a steel twisted wire, it has the
potential to not only saw in to the bend 16, but also into the
insert 80 of FIG. 8. By having rollers, the bend liner can be
adapted to handle the use of wire rope pigs such as are illustrated
in U.S. Pat. No. 7,998,276.
[0041] Referring now to FIG. 12, thruster pig assembly 120 is shown
in pipeline 12, having ball.times.ball socket adaptors 122A and
122B on each end, then ball.times.ball adaptors 124A and 124B
connected, then ball socket.times.buff-weld adaptors 126A and 126B
at each end for welding to coiled tubing strings. Thruster pig
assembly 120 is similar to thruster pig assembly 48 seen on FIG. 7,
except thruster pig assembly 48 was a terminal type for the end of
the coiled tubing for primarily pulling out into the pipeline. The
ability to use thruster pig assembly 48 for returning forces is
limited by column buckling forces of the coiled tubing. Thruster
pig assembly 120 is intended for the middle of a coiled tubing
string for the opposite purpose of pulling the coiled tubing back
rather than pulling it out. Otherwise the mechanisms of the pigs
can be similar.
[0042] Referring now to FIG. 13 which is an enlargement of the
center section of FIG. 12, thruster pig assembly 120 is shown in
greater detail. Thruster pig 120 has 3 central bores at
approximately 30 degrees, 130, 132, and 134. Bore 130 is only
partially shown and simply communicates the flow inside the central
bore 136 in either direction as indicated by arrows 138 and 140.
Bore 132 directs flow as indicated by arrows 142A-F from the
proximate end of the pig to the distal end during travel of the
coiled tubing out into the pipeline. Check valve 144 has a weak
spring 146 so as to block reversed flow but not to cause a
significant pressure differential in the outward trip. On the trip
out to the blockage located in the pipeline, it is as if this
thruster pig does not exist.
[0043] Bore 134 has check valve 150 with stronger spring 152 which
will cause a predetermined pressure differential across thruster
pig assembly 120 when flow is coming in the direction of arrows
154A-E. This predetermined pressure differential will combine with
the cross sectional sealing area within the pipeline to give a
predetermined force to assist the coiled tubing in being recovered
from the pipeline. Rather than long lengths of coiled tubing being
drug back by pulling around a bend such as was indicated at 16, it
can be pulled by the force across one or more thruster pig
assemblies 120. The dominant force in coiled tubing will be tension
without the column buckling tendency, but some limited force can
also push the coiled tubing ahead of the pig.
[0044] Thruster pig assembly 120 is illustrated as being welded.
into the coiled tubing string but other options are available. Slip
type connectors and threaded connectors are available in some
cases. Specifically in the case of slip type connectors, coiled
tubing can be run through the thruster pig assembly until the
appropriate connection point, the slips set, and then the pig can
be run with the coiled tubing. Design requirements of this type pig
make it increasingly difficult to pass 5D bends, and tend to be
limited to applications with larger radius bends.
[0045] Sealing cups 160 comprise a metal seal carrier 162 and a
resilient cup member 164. O-ring type seal 165 seals between the
metal seal carrier 162 and the pig 166. The two sealing cups 160
have an inner spacer ring 167 with O-ring type seals 168 and 169
which allows the two sealing cups 160 to be identical and perform
the additional benefit of redundant sealing. It will be noted that
there is a gap inside each of the sealing cups 160 as the internal
bore 170 of the sealing cups 160 is larger than the outer diameter
172 of pig body 166. Pig guide bushings 180 and 182 are of a low
friction material mount to pig body 166 and assist the thruster pig
assembly to slide along the pipeline, but as they must be smaller
than the internal diameter of the pipeline, they will slide
eccentrically to the centerline of the pipeline. This means that if
sealing cups 160 are rigidly mounted to pig body 174, they will be
pressed more tightly on one side that the other, accentuating the
wear on that side and limiting the service life of the thruster pig
assembly 120. However, sealing cups 160 are mounted in such a way
as to have clearances to allow the sealing cups 160 to remain
concentric to the pipeline bore and give a uniform lower stress to
the resilient cup members 164. This means rather than the resilient
cup members 164 having to support the weight of all the metal parts
of the thruster pig assembly and handle any moments caused from the
coiled tubing, they simply glide in a centralized state.
[0046] Referring now to FIG. 14, thruster pig assembly 120 is shown
going through an extreme pipe bend such as was indicated as 16 in
FIG. 1.
[0047] Referring now to FIG. 15 which is an enlargement of the
central section of FIG. 14, pig guide bushings 180 and 182 are
shown to be close to contacting the pipeline internal diameter at
180 and 182 and various parts of pig body 174 is close to
contacting the pipeline internal diameter at 184, 186, 188, and
190. If the sealing cups 160 were held in a centralized position
they would be crushed on the inside of the bend and would not be
touching the inside of the pipe internal bore on the outside of the
bend. In FIG. 15, sealing cups 160 have been allowed to slide down
and to the left in the view to not be crushed on the upper right
side and to remain in sealing contact on the lower left side. The
ability of sealing cups 160 to float relative to the pig body
improve their performance both in straight long distance travel and
in short distance travel around bends.
[0048] The particular embodiments disclosed above are illustrative
only, as the invention may be modified and practiced in different
but equivalent manners apparent to those skilled in the art haying
the benefit of the teachings herein. Furthermore, no limitations
are intended to the details of construction or design herein shown,
other than as described in the claims below. It is therefore
evident that the particular embodiments disclosed above may be
altered or modified and all such variations are considered within
the scope and spirit of the invention. Accordingly, the protection
sought herein is as set forth in the claims below.
* * * * *